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| Order this document by MC33468/D Variable Frequency Micropower Step-up DC-DC Converter The MC33468 is a micropower step-up switching voltage regulator, specifically designed for handheld and pager applications, to provide a regulated output voltage using a minimum of external parts. This device features a quiescent bias current of 3.0 A typical. The MC33468 features a highly accurate voltage reference, an error amplifier, an oscillator, a variable frequency modulation (VFM) controller, a drive pin (EXT) for an external transistor, and feedback resistors. The Vout pin is fixed at 2V in the IC. The output of the converter with an inductor, a diode, a capacitor, a drive transistor, and feed-back resistors can have an output of 30V. MC33468 VARIABLE FREQUENCY MICROPOWER DC-to-DC CONVERTER SEMICONDUCTOR TECHNICAL DATA MC33468 Features: * Low Quiescent Bias Current of 3.0 A * * * * * High Output Voltage Accuracy of 2.5% Low Startup Voltage of 0.8 V at No Load Output Voltage Set With External Resistors Operating Temperature Range: -40C to +85C Surface Mount Package N SUFFIX PLASTIC PACKAGE CASE 1212 (SOT-23-5) Quantity 3000 1 5 ORDERING INFORMATION Device MC33468SN-20ATR * "XX" denotes the lot number. Output Voltage 2.0 Marking 0KXX* Reel Size 7" Tape Width 8 mm PIN DESCRIPTION PIN CONNECTIONS Description Ground Input Ground Vdd EXT 1 2 3 (Top View) 4 N/C 5 VOUT AAAAAAAAAAAAAA A AAAAAAAAAAAAAAAAAAAAA AA AAAAAAAAAAAAAA A AA AAAAAAAAAAAAAAAAAAAAA AA AAAAAAAAAAAAAAAAAAAAA AA AAAAAAAAAAAAAAAAAAAAA AA AAAAAAAAAAAAAAAAAAAAA AA AAAAAAAAAAAAAAAAAAAAA AAAAAAAA AAAAAAAAAAAAAAAAAAAAA AA A AAAAAAAAAAAAAAAAAAAAA AAAAAAAA A 1 2 3 4 5 GND VDD EXT NC External Transistor Drive No Connection VOUT Voltage Output Pin (Fixed at 2V) Pin No. Symbol Representative Block Diagram 2 VDD 3 EXT Oscillator Drive 5 VOUT Vref 1 Gnd MOTOROLA ANALOG IC DEVICE DATA 1 MC33468 MAXIMUM RATINGS (TC = 25C, unless otherwise noted.) VOUT , OUTPUT VOLTAGE (V) 30 EFFICIENCY AAA A A A A A A AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AA A A A A A A AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAA A A A A A AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAA A AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAA AAA A A A A AAAAAAAAAAAAAAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AA A A A A A AAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAA AAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAA AAA A AA AAAAAAAAAAAAAAAAAAAAAAAAA A AA AAA A AA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAA AA AAAAAAAAAAAAAAAAAAAAAAAAA A AA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAA AA AAA A A AAAAAAAAAAAAAAAAAAAAAAAAA A AA AAA A AA AAAAAAAAAAAAAAAAAAAAAAAAA A AA AAAAAAAAAAAAAAAAAAAAAAAAA A AA AAAAAAAAAAAAAAAAAAAAAAAAA A AA AAAAAAAAAAAAAAAAAAAAAAAAA A AA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAAA A AA AAAAAAAAAAAAAAAAAAAAAAAAA A AA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAA A Power Supply Voltage (Transient) VDD VDD 12 10 V V V Power Supply Voltage (Operating) External Pin Voltage VEXT IEXT -0.3 to VDD + 0.3 50/50 EXT Pin Source/Sink Current mA Power Dissipation and Thermal Characteristics N Suffix, Plastic Package Case 1212 (SOT-23-5) Maximum Power Dissipation @ TA = 250C Thermal Resistance, Junction-to-Air Operating Junction Temperature Operating Ambient Temperature Storage Temperature Range PD RJA TJ TA 150 667 125 mW C/W C C C -40 to +85 Tstg -55 to +125 Rating Symbol Value Unit ELECTRICAL CHARACTERISTICS (VDD = 1.9 V, TA = 25C, unless otherwise noted.) Characteristic Symbol Min OSCILLATOR Frequency fosc - - Typ Max Unit Note1 180 0.7 75 - kHz V B B B Oscillator Minimum Supply Voltage (IO = 0 mA) Oscillator Duty Cycle VDD D 0.8 - 65 % EXT OUTPUT ON State Source Current (VEXT = GND) OFF State Sink Current (VEXT = 1.9 V) Output Voltage Isource Isink VOUT IQ IQ RVout 1.5 1.5 - - - - mA mA C D TOTAL DEVICE 1.950 - - - 2.000 15 - 3.0 2.050 25 - - 5.0 V Quiescent Bias Current (VOUT = 1.9 V, IO = 0 mA) Quiescent Bias Current (VOUT = 2.1 V, IO = 0 mA) Internal Resistor (VOUT to GND) Output Voltage Temperature Coefficient IOUT = 10 mA, -40C TA 85C A A A A E 2.0 MW DVOUT DTA 50 ppm/oc 1. Indicates test circuits shown on next page. Figure 1. Output Voltage versus Output Current 40 Vin = 3.6 V 35 60 50 40 25 30 20 20 80 70 Figure 2. Efficiency versus Output Current Vin = 3.6 V 0 20 40 60 0 20 40 60 IOUT, OUTPUT CURRENT (mA) IOUT, OUTPUT CURRENT (mA) (c) Motorola, Inc. 1999 Rev 1, 09/1999 2 MOTOROLA ANALOG IC DEVICE DATA MC33468 A VDD A EXT GND Oscilloscope VOUT A EXT GND B VDD VOUT C VDD VOUT EXT GND D VDD VOUT EXT GND E VDD VOUT EXT GND A Figure 3. Test Circuit Schematics MOTOROLA ANALOG IC DEVICE DATA 3 MC33468 DEFINITIONS Quiescent Bias Current - Current which is used to operate the switching regulator chip and is not delivered to the load. Leakage Current - Current drawn through a transistor junction, under a specified collector voltage, when the transistor is off. on-time of the transistor switch. During the off-time of the transistor switch, the inductor current ramps down to zero and remains at zero until another switching cycle begins. Since the VDD pin is connected to the input no external startup circuit is needed. Oscillator The oscillator frequency, is internally programmed to 180 kHz. The duty ratio of the oscillator is designed for a constant value of 0.75 nominal. Hence the nominal on-time of the power switch is: 0.75 D ton s f osc (180 kHz) FUNCTIONAL DESCRIPTION Introduction The MC33468 is a monolithic power switching regulator optimized for dc-to-dc converter applications where power drain must be minimized. The MC33468 uses Variable Frequency Modulation to step up the input DC voltage to a higher accurate output voltage. Potential applications include low power consumer products and battery powered portable products. Typical application circuits are shown in Figure 4. Operating Description The MC33468 converter operates as a fixed on-time, variable off-time voltage mode ripple regulator. Operation is intended to be in the discontinuous mode, where the inductor current ramps up to a peak value which is greater than or equal to twice the value of the dc input current during the + + +4.16 Feedback Comparator The output voltage is sensed and fed to a high speed comparator noninverting input through an internal resistive divider. The comparator inverting input is connected to an internally trimmed reference. With a voltage mode ripple converter operating under normal conditions, output switch conduction is initiated and terminated by the oscillator, off-time is controlled by the high speed voltage feedback comparator. Figure 4. Typical 2.0 V Application with BJT VOUT VDD VIN EXT Gnd VOUT Figure 5. Design Equations for Step-Up Calculation ton L Equation D f osc t (n)(Vin) (ton) P 2 (V in IL(avg) IL(pk) Vripple(pp) * O Iin V sat)(t on) L [ (ton)(I ) O (C ) O The following converter design characteristics must be chosen: Vin - Nominal Operating dc input voltage VO - Desired dc output voltage IO - Desired dc output current Vripple(pp) - Desired peak-to-peak output ripple voltage. For best performance the ripple voltage should be kept to a low value since it directly affects regulation. Capacitor CO should have a low equivalent series resistance (ESR). NOTE: 1. Vsat - Saturation voltage of the switching transistor. n - Estimated circuit efficiency. 4 MOTOROLA ANALOG IC DEVICE DATA MC33468 Figure 6. Typical 2.0 V Application with MOSFET VOUT VDD VIN EXT GND VOUT If input voltage is high enough, higher efficiency may be obtained by using a MOSFET as the switch transistor, in which no gate resistor or capacitor is needed. MOSFET and BJT voltage rating (VDS and VCE) should be high enough to allow for spikes in voltage. Figure 7. Typical Application for Output Voltages Over 2.0 V L1 D1 VOUT R1 VDD (2.0 V) VIN EXT Q1 R2 GND VOUT COUT Inductor (L1) Diode (D1) Capacitor (COUT) Transistor (Q1) Resistor (R1) Resistor (R2) CD54 (15 mH) MBRD540T1 47 mF (Tantalum type) MMFT3055VL 150 kW 10 kW When choosing the output capacitor, ensure that the capacitor voltage is higher than Vout. Select an inductor with low DC resistance and high saturation. A Schottky diode is recommended for a lower voltage drop and faster switching. Use external resistors that are much smaller resistance than the resistance internal to the IC (minimum of 2 MW). When R1 is much less than the internal resistance, the error is minimized. MOTOROLA ANALOG IC DEVICE DATA 5 MC33468 OUTLINE DIMENSIONS N SUFFIX PLASTIC PACKAGE CASE 1212-01 (SOT-23) ISSUE O A D B A2 0.05 S NOTES: 1. DIMENSIONS ARE IN MILLIMETERS. 2. INTERPRET DIMENSIONS AND TOLERANCES PER ASME Y14.5M, 1994. 3. DATUM C IS A SEATING PLANE. A1 L DIM A1 A2 B C D E E1 e e1 L L1 E 5 1 2 4 3 E1 L1 e e1 B 5X C M 0.10 CB S A S C MILLIMETERS MIN MAX 0.00 0.10 1.00 1.30 0.30 0.50 0.10 0.25 2.80 3.00 2.50 3.10 1.50 1.80 0.95 BSC 1.90 BSC 0.20 --- 0.45 0.75 Recommended Footprint for Surface Mount Applications 0.7 MAX. 1.0 2.4 0.95 1.9 0.95 (Unit: mm) SOT-23-5 6 MOTOROLA ANALOG IC DEVICE DATA MC33468 NOTES MOTOROLA ANALOG IC DEVICE DATA 7 MC33468 Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. "Typical" parameters which may be provided in Motorola data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. Motorola does not convey any license under its patent rights nor the rights of others. Motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Motorola product could create a situation where personal injury or death may occur. Should Buyer purchase or use Motorola products for any such unintended or unauthorized application, Buyer shall indemnify and hold Motorola and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that Motorola was negligent regarding the design or manufacture of the part. Motorola and are registered trademarks of Motorola, Inc. Motorola, Inc. is an Equal Opportunity/Affirmative Action Employer. Mfax is a trademark of Motorola, Inc. How to reach us: USA / EUROPE / Locations Not Listed: Motorola Literature Distribution; P.O. Box 5405, Denver, Colorado 80217. 1-303-675-2140 or 1-800-441-2447 Customer Focus Center: 1-800-521-6274 MfaxTM: RMFAX0@email.sps.mot.com - TOUCHTONE 1-602-244-6609 ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd.; Silicon Harbour Centre, Motorola Fax Back System - US & Canada ONLY 1-800-774-1848 2, Dai King Street, Tai Po Industrial Estate, Tai Po, N.T., Hong Kong. - http://sps.motorola.com/mfax/ 852-26629298 HOME PAGE: http://motorola.com/sps/ JAPAN: Motorola Japan Ltd.; SPD, Strategic Planning Office, 141, 4-32-1 Nishi-Gotanda, Shinagawa-ku, Tokyo, Japan. 81-3-5487-8488 8 MC33468/D MOTOROLA ANALOG IC DEVICE DATA |
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